Tool Position Deviation Analysis for Workpiece Surface Defect Detection
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Solution Overview
Problem
Current methods for detecting surface quality issues in workpieces, such as scratches and artefacts, require high precision equipment and manual visual assessment, leading to increased time and cost due to the small size of these defects and the need for precise tool position measurement.
Innovation Solution
A method that estimates surface quality by determining a reference signal representing the difference between ideal and real tool positions during a reference phase and a test signal during the finishing operation, using statistical features like mean value and standard deviation to identify anomalies, allowing for automated detection without additional measurement equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high precision equipment and manual visual assessment are used to detect surface quality issues, then measurement precision is improved, but device complexity and loss of time increase
Solution Approach 1:
The patent introduces an intermediary measurement approach by using tool position deviation as a proxy indicator for surface quality. Instead of directly measuring the workpiece surface with complex high-precision equipment, the system measures the deviation between actual and nominal tool positions during machining, which indirectly reflects surface quality issues. This intermediary measurement method simplifies the measurement system while maintaining detection capability.
Solution Approach 2:
The patent replaces direct mechanical surface measurement systems with a computational approach based on tool position data. Instead of using complex optical or tactile measurement equipment to directly inspect the workpiece surface, the system substitutes this with analysis of tool position deviations recorded during the machining process, reducing measurement equipment complexity while maintaining detection precision.
2Measurement precision
If high precision equipment and manual visual assessment are used to detect surface quality issues, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary action by collecting and analyzing tool position deviation data during the machining process itself, before the workpiece leaves the machine tool. This allows surface quality assessment to be integrated into the manufacturing process rather than being performed as a separate post-processing inspection step, thereby maintaining measurement precision while eliminating additional detection time.
Solution Approach 2:
The patent ensures continuity of useful action by making the surface quality detection continuous throughout the machining process. The tool position deviation is measured continuously during machining, allowing real-time quality assessment without interrupting the manufacturing process for separate inspection operations, thus maintaining precision while reducing total detection time.
3Productivity
If automated detection method using tool position signals is used, then productivity is improved, but measurement precision may worsen
Solution Approach 1:
The patent implements feedback by using the measured tool position deviations to infer surface quality conditions. The system continuously monitors tool position signals during machining and uses this feedback information to detect surface quality issues automatically. This feedback mechanism enables automated detection that maintains precision by relying on accurate tool position measurement data rather than direct surface measurement.
Solution Approach 2:
The patent creates a copy of the surface quality information through tool position deviation data. Instead of directly measuring the workpiece surface, the system captures an indirect copy of surface quality conditions embedded in the tool position signals during machining. This copied information can be analyzed automatically to detect surface defects, improving productivity while maintaining detection accuracy through computational analysis.
Data Source
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AI summary
The quality of a workpiece (7) shall be checked in a simple way. Therefore, there is provided a method including finishing a surface section of the workpiece (7) with a manufacturing device (1) (S1), determining a reference signal (13) representing a time dependent difference between an ideal tool position and a real tool position of a tool (3) of the manufacturing device (1) in a reference phase when finishing the workpiece (7) (S2), determining a test signal (16) representing a time dependent difference between an ideal tool position and a real tool position of a tool (3) of the manufacturing device (1) in an operation phase when finishing the workpiece (7) (S3), determining a mean value (μ) and a standard deviation value (o) from the reference signal (13) (S7), determining data points (17) of the test signal (16), where the test signal (16) deviates from the mean value (μ) more than a defined multiple of the standard deviation value (o) (S8) and estimating the surface quality of the workpiece (7) by using the determined data points (17) (S9).